Article conveyor systems conventionally comprise serially arranged pairs of conveyor belts for conveying the particular articles in a predetermined direction. Each one of the conveyor belts comprises a closed or endless loop structure wherein opposite ends of the closed or endless loop are respectively routed around rollers, at least one of which comprises a conveyor belt drive roller. The inner runs or inner portions of each pair of closed or endless looped conveyor belts are disposed immediately adjacent to each other in an opposed, side-by-side, or laterally or transversely spaced, mode with respect to each other along the direction of conveyance. In this manner, the opposed inner runs or inner portions of the conveyor belts cooperate together so as to effectively encounter and operatively engage the articles therebetween whereby the articles are effectively entrained with the opposed conveyor belts so as to be conveyed thereby in the predetermined direction of conveyance. The drive roller operatively associated with each conveyor belt is conventionally driven by means of a drive system which comprises, for example, a high-voltage electric drive motor and a mechanical drive system operatively interconnecting the electric motor output shaft and the rotary drive shaft upon which the drive roller is fixedly mounted. Such mechanical drive systems generate and radiate an inordinate amount of noise. In addition, while the electric drive motors, respectively associated with each one of the conveyor belts comprising each pair of oppositely disposed conveyor belts, can be suitably regulated so as to cause their output shafts to be rotated at a predetermined rotary speed which would, in turn, cause the conveyor belt drive rollers to likewise be rotated at the same rotary speed, due to various factors inherently characteristic of conventional conveyor belt drive systems, it often happens that the opposed conveyor belts are not in fact driven at the same lineal rate of speed.
Accordingly, a speed differential effectively exists between the oppositely disposed inner runs or inner portions of the opposed conveyor belts, and when these oppositely disposed inner runs or inner portions of the opposed conveyor belts, being operated at their different lineal rates of speed, operatively engage the opposite surface portions of the articles being conveyed between and by the oppositely disposed inner runs or inner portions of the opposed conveyor belts, serious operational and environmental problems occur. More particularly, as a result of the engagement of the opposite surface portions of the articles by the oppositely disposed inner runs or inner portions of the opposed conveyor belts conveying the articles along the longitudinal extent of the overall conveyor system, frictional forces are generated between the opposite surface portions of the articles and the oppositely disposed inner runs or inner portions of the opposed conveyor belts as a result of the effective mechanical scrubbing of the opposite surface portions of the articles by the oppositely disposed inner runs or inner portions of the opposed conveyor belts. In light of such mechanical scrubbing of the opposite surface portions of the articles by the oppositely disposed inner runs or inner portions of the opposed conveyor belts, the articles being conveyed by the opposed conveyor belts are subjected to highly erosive forces. These highly erosive forces not only effectively compromise the structural integrity of each article being conveyed by the opposed conveyor belts, but in addition, result in the generation of atmospherically suspended cellulose particulates which not only constitute a human health hazard but, still further, present a potentially explosive atmospheric condition and hazardous work environment.
Continuing still further, it is noted, particularly in those conveying systems wherein the articles, such as, for example, mail pieces, are desirably conveyed, or sought to be conveyed, at substantially high rates of speed, such as, for example, within the range of two hundred inches per second (200 ips), that the articles or mail pieces are effectively the aerodynamic equivalent of a flat plate. As such, the articles or mail pieces will be subjected to aerodynamic forces which can be significantly disruptive to the stable conveyance of the articles or mail pieces when the articles or mail pieces are in fact conveyed at the afore-noted desirable high rates of speed within such article or mail piece conveying systems. More particularly, the air flows or air currents within such article or mail piece conveying systems are not always uniform or precisely symmetric with respect to the longitudinal axis of the conveyance path along which the articles or mail pieces are being conveyed. In addition, surface imperfections or irregularities may be present upon the conveyor belts. Still yet further, due to the airflows past the articles or mail pieces, which are structurally equivalent to a finite wing or airfoil, air circulation, currents, downflow, downwash, and momentum forces result in the generation of tip vortices. These various forces and vortices cause the articles or mail pieces to undergo or exhibit destabilizing fluctuation, flutter, or oscillatory movements which also contribute to the development of mechanical or structural interaction or engagement between the articles or mail pieces and the conveyor belts.
This dynamic situation again results in frictional forces being generated between the opposite surface portions of the articles or mail pieces and the oppositely disposed inner runs or inner portions of the opposed conveyor belts whereby mechanical scrubbing of the opposite surface portions of the articles or mail pieces, by the oppositely disposed inner runs or inner portions of the opposed conveyor belts, effectively occurs. In turn, the articles or mail pieces being conveyed and mechanically scrubbed by the oppositely disposed conveyor belts are subjected to highly erosive forces whereby, again, such highly erosive forces not only effectively compromise the structural integrity of each article or mail piece being conveyed by the oppositely disposed conveyor belts, but in addition, result in the generation of atmospherically suspended cellulose particulates which not only constitute a human health hazard but, in addition, present a potentially explosive atmospheric condition and hazardous work environment.
A need therefore exists in the art for a new and improved article or mail-piece conveyor belt drive system, wherein oppositely disposed, inner runs or inner portions of the endless looped conveyor belts can cooperate together so as to convey articles or mail pieces along the longitudinal extent of the conveyor system at a substantially high rate of speed and in a stabilized manner, wherein the articles or mail pieces will not be subjected to aerodynamic forces which can be significantly disruptive to the stable conveyance of the articles or mail pieces when the articles or mail pieces are in fact conveyed at substantially high rates of speed within such article or mail piece conveying systems, and wherein the article or mail pieces, which simulate finite wing or air foil structures, will not be subjected to destabilizing air circulation, currents, downflow, downwash, or momentum forces such that tip vortices will not be generated whereby the articles or mail pieces will not undergo or exhibit fluctuation, flutter, or oscillation movements so as to effectively prevent the development of mechanical or structural interaction or engagement between the articles or mail pieces and the oppositely disposed, inner runs or inner portions of the conveyor belts whereby, in turn, frictional forces will be prevented from being generated between the opposite surface portions of the articles or mail pieces and the oppositely disposed inner runs or inner portions of the opposed conveyor belts whereby mechanical scrubbing of the opposite surface portions of the articles or mail pieces, by the oppositely disposed inner runs or inner portions of the opposed conveyor belts, will likewise be prevented from occurring so as to, in turn, effectively prevent the articles or mail pieces from being subjected to highly erosive forces which would not only effectively compromise the structural integrity of each article or mail piece being conveyed by the oppositely disposed conveyor belts, but in addition, would result in the generation of atmospherically suspended cellulose particulates which would not only constitute a human health hazard but, in addition, would present a potentially explosive atmospheric condition and hazardous work environment.